Just finished Amnesia and....

[Googolplex]

You will laugh, but HPL1 feels more realistic to me.
If you pick up objects, you will feel the gravity, or if you open a door, you will feel the weight.

In Amnesia you can pick up a chair for example and you feel nothing about gravity. There is no mass.

And in Amnesia are less puzzles using physics.
In Penumbra you can tinker with objects. This engine is older, but the physics feels more realistic to me.